Helio Castroneves Says Kirstie Alley Is 'Fantastic' on Dancing with the Stars

The winner of Dancing With the Stars season 5 had a hunch that the former Cheers actress would be dynamite on the dance floor. "You can't try to be a professional," Castroneves told PEOPLE at the Blacks' Annual Gala at Eden Roc Renaissance Hotel in Miami. "You have to be free when you're dancing. When I heard that Kirstie would be on the show, I said, 'She's going to be good.' "

And after he saw her doing the quickstep? "I think she was fantastic," he says. "More than anything, you've got to have fun, and that's what she's doing. We're going to see her progress more and more as the weeks go on."

Although Alley has been the brunt of jokes about her weight, Castroneves doesn't think it will be a problem. "She seems very comfortable on the dance floor," he says. "She's a natural, no matter what size she is."

But is Alley his pick to win? Maybe not. "There are some good dancers this year, some tough competition," Castroneves says. "Chelsea Kane is really great. But I personally like the Karate Kid. Ralph Macchio looks like he has been dancing for years. He could take it all."